含1,2,3-三氮唑液晶化合物及多苯環芳香族亞醯胺衍生物之合成與分子自組裝及其在有機薄膜電晶體之研究

Abstract

本論文主要是研究小分子和聚合物的分子自組裝。第一部分利用click chemistry合成含1,2,3－三氮唑液晶化合物並探討其分子自組裝奈米結構。第二個部分則合成多苯環芳香族亞醯胺衍生物並應用在溶液製程傳電子有機薄膜電晶體上。 本研究第一部分，合成一系列包含4-[1,2,3]-triazolephenyl 4-alkoxybenzoate 液晶基團及β-D-galactopyranoside親水基醣類的新穎掌性兩性液晶化合物。所有所合成的化合物皆具有chiral smectic A液晶相，且這些小分子兩性化合物在水溶液中自組裝聚集，藉由增加疏水尾端的碳鏈長度，其型態由平板狀到螺旋形態。另外利用click chemistry結合2-azidoethyl-2,3,4,6-tetraacetyl-β-D-galactopyranoside 及1-biphenyl-acetylene 4-alkynyloxybenzoate的三個含醣乙炔單體也被合成，所得的單體利用WCl6-Ph4Sn聚合成側鏈液晶聚乙炔。所有的單體與聚合物都具有chiral smectic A液晶相。單體在水溶液中自組裝也是隨著增加疏水尾端的碳鏈長度，其型態由平板狀到螺旋形態。此外，這些螺旋的結構可以在摩擦的PI配向膜上規則排列。在聚合物自組裝方面，含醣液晶聚乙炔，成功於THF和甲醇的co-solvent 系統自組裝形成helical cables的螺旋結構。 本研究第二部分主要致力於發展可溶性且在空氣中是穩定的傳電子有機半導體。這系列合成由四個不同平面大小的苯環芳香族中心核及四個含氟側鏈取代基所組成的二十個有機半導體，並探討不同中心核大小，含氟側鏈取代基與柔軟鍊長短對電荷遷移率的影響。電晶體採用 top contact/botton gate，有機半導體利用旋轉塗布成膜在利用hexamethyldisilazane (HMDS)修飾的SiO2/Si wafer上，並於氮氣下與一般大氣下量測其電晶體特性。P(1)、P(2)和P(3)的電子遷移率分別是4.71×10-9, 1.03×10-8, and 4.3×10-8 cm2V-1s-1 ，隨著柔軟鏈的增長，電子遷移率增加。P(-)和PCl(-)在氮氣下的最佳電子遷移率分別是3.88×10-4 and 5.31×10-4 cm2V-1s-1。然而只有PCl(-)在空氣中有較佳的薄膜電晶體電性，其電子遷移率為3.61×10-4 cm2V-1s-1。

The goal of this research is to study the self-assembly of small molecules and polymers. The first part of this study is focused on the synthesis and self-assembled nanostructures of 1,2,3-triazole liquid crystals via click chemistry. The second part is to study the synthesis of polycyclic aromatic diimide derivatives and their application on the solution-processed n-type organic thin-film transistors. In the first part, a series of novel chiral amphiphilic liquid crystals, which contain 4-[1,2,3]-triazolephenyl 4-alkoxybenzoate mesogens and β-D-galactopyranoside end-group, were synthesized. All obtained compounds were exhibited a chiral smectic A phase. The self-assembling behavior of these liquid crystal amphiphiles in the solution, which exhibited high segregation strength for phase separation, was studied by electron microscopy. The morphological transformation of self-assembled chiral amphiphilic liquid crystals, from a platelet-like morphology to helical twists, was obtained by increasing the length of the hydrophobic alkyl tail. In addition, three kinds of chiral saccharide-containing liquid crystalline acetylenic monomers were prepared by click reaction between 2-azidoethyl-2,3,4,6-tetraacetyl-β-D-galactopyranoside and 1-biphenyl- acetylene 4-alkynyloxybenzoate. The obtained monomers were polymerized by WCl6-Ph4Sn to form three side-chain LC polyacetylenes. All monomers and polymers show a chiral smectic A phase. Self-assembled hiearchical superstructures of the chiral saccaride-containing LCs and LCPs in solution state were studied. Due to the LC behavior, these molecules exhibit a high segregation strength for phase separation in dilute solution. The self-assembled morphology of LC monomers was dependent upon the alkynyloxy chain length. Increasing the alkynyloxy chain length caused the self-assembled morphology to change from a platelet-like texture (K6E) to helical twists morphology (K11E and K12E). Furthermore, the helical twist morphological structure can be aligned on rubbed polyimide layer to form two dimensional ordered helical patterns. In contrast to LC monomers, K11P was self-assembled into much more complicated morphologies, including nanospheres and helical nanofibers. These nanofibers are evolved from the helical cables ornamented with entwining nanofibers upon natural evaporation of the solution in a mixture with a THF/methanol ratio of 3:7. The second part of the work is mainly devoted to the development of new soluble and air-stable n-ytpe semiconducting materials. The synthesis and comprehensive characterization of 20 organic semiconductors comprised of four different sizes of polycyclic aromatic cores and five different fluorinated substituents are described. The influences of the structural modifications of the fluorinated substituent, spacer and central core on the charge mobility were examined. Top contact/botton gate organic thin film transistor devices were constructed by spin-coating process of these derivatives on SiO2/Si wafer that had been pretreated with hexamethyldisilazane (HMDS). The electrical characterization of all devices was accomplished in a nitrogen atmosphere as well as in air. The mobilities of P(1), P(2) and P(3) were measured to be 4.71×10-9, 1.03×10-8, and 4.3×10-8 cm2V-1s-1, respectively. With longer spacer inserted between perylene core and fluorinated dendrons, the mobility is increased. The highest mobilities of P(-) and PCl(-) are 3.88×10-4 and 5.31×10-4 cm2V-1s-1, respectively, as measured in the glove-box. However, only PCl(-) shows good OTFT behavior and comparable mobility of 3.61×10-4 cm2V-1s-1 as measured in air. The result demonstrates that Cl4-PTCDA core (perylene with 4 chloro substituents) can serve as a good candidate for OTFT.